Means for governing fluid pump in rotary well drilling rig



W. CLARK July 1o, 1962 MEANS F'OR GOVERNING FLUID PUMP IN ROTARY WELLDRILLING RIG Filed April 50, 1958 2 Sheets-Shet 1 villin- INVEN TOR.WALLACE CLARK,

ATTORNEYS.

July 1o, 1962 W, CLARK 3,043,380

MEANS FOR GOVERNING FLUID PUMP IN ROTARY WELL DRILLING RIG Filed April50, 1958 2 Sheets-Sheet 2 34 f u; i 2l INVENTOR. WALLACE CLARK,

ATTORNEYS United States Patent C) 3,043,380 MEANS FOR GOVERNING FLUIDPUMP IN ROTARY WELL DRILLING RIG Wallace Clark, RR. 10, Box 409,Indianapolis, Ind. Filed Apr. 30, 1958, Ser. No. 731,930 6 Claims. (Cl.175-26) This invention relates to well drilling and more particularly torotary drilling rigs in which the drill bit is rotated by means of ahydraulic motor suspended within the well bore at the bottom of thehole.

In this type of rotary well drilling rig the drill motor, which issuspended within the well bore by sections of casing, tubing or drillpipe, is a hydraulic motor adapted to be driven by a fluid which ispumped through the drill pipe. Mud is the commonly used fluid. It isdelivered to the casing, tubing, or drill pipe from a reservoir b-ymeans of a pump which is usually set to deliver the mud at a constantvolume, but which volume should be advisably controlled to compensatefor hydraulic slip in the drill bit motor. If the rate of low requireschanging, so as to maintain the speed of rotation of the drill bitmotor, or to hold the speed of the motor constant to compensate forhydraulic slip resulting from variations in its required torque, or toprevent stalling, such alteration must be done manually, if at all.

In drilling a deep well, the drill bitpasses through various strata,some of which may be very hard and dense and others of which may besoft, porous and the like, and o it is desirable to maintain the speedof the drill bit constant regardless of the particular conditionsencountered or the bit may stall. For example, if the drill bitencounters hard rock, it will by nature rotate at a higher rate ofspeed, Whereas when the drill bit runs into a soft formation, it willdig in, reducing the rotative speed of the drill bit, assuming that theweight on the bit is constant, and the result may be a stalled or stuckbit with much time loss.

It is, therefore, a principal object of the present invention to providea method and means for automatically maintaining constant rotative speedof the drill bit regardless of the Work required by the bit and in spiteof the varying hydraulic slip, which must naturally vary with the torquerequired to cut the different types of formation from hard to soft.

A further object of the invention is the provision of a method and meansfor governing the operation of the pump which supplies fluid to thedrill bit motor in accordance with the torque established in the drillpipe or drilling string by the drill bit motor.

This is accomplished by positively rotating the drill pipe at a slowconstant rate of speed and by utilizing the torque of the drill pipedriving means as a reactor responsive to the torque of the drill bitmotor. In this connection, it should be explained that the power ortorque required to rotate the drill pipe at constant speed will beaffected only by variations in the torque reaction of the drill bit.This is because the friction of the drill pipe against the drilling mudand against the walls and lining of the well is constant at a givendepth, the rota- -tive speed of the drill pipe is constant, and theinertia of the drill pipe need not be taken into consideration. As willbe explained more fully hereinafter, the torque reaction of the drillpipe driving means is utilized to control the operating speed of thepump supplying fluid to the drill bit motor.

Reference is now made to the accompanying drawings wherein:

FIGURE 1 is an elevational view with parts broken away showing a welldrilling rig in accordance with the invention.

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FIGURE 2` is an enlarged fragmentary plan view with parts broken awayillustrating the mounting of the drive motor in its trunnions.

FIGURE 3 is a fragmentary and diagrammatic representation of amodification.

FIGURE 4 is a schematic representation of another modification.

Referring now to FIGURE l of the drawings, I have therein illustrated anexemplary rotary drilling rig comprising a string of drill pipe 10extending downwardly into a-well 11, the drill pipe mounting at itslowermost end a drill bit motor 12 to which a drill bit 13 isoperatively connected. It will be understood that the motor will be ofhydraulic character and reference is hereby made to Clark Patent2,898,087, dated August 4, 1959 and entitled Well Drilling Apparatus andMethod, wherein there is disclosed a drill bit motor and bit assemblycapable of use in conjunction with the instant invention. At its upperend, the string of drill pipe is ixedly secured to a polygonalkellywhich is slidably journaled in a rotary table 15 having a peripheralbevel gear 16. The kelly extends upwardly beyond the rotary table Whereit is suspended, as by means of hook 17, from a derrick, a portion ofwhich is indicated at 18. At its upper end the kelly mounts a swivelconnection 19 connected to a uid supply hose 2d through which thedrilling fluid is supplied to the drill pipe, it being understood thatthe kelly is hollow so that the fluid may flow. downwardly therethrough.In the embodiment illustrated, the fluid supply hose 20 is connected toa pump 21 having a conduit 22 for supplying fluid from a reservoir orother source of supply (not shown). The pump is adapted to be driven bya prime mover 23 which in this instance, comprises an internalcombustion engine, the crank shaft of the engine being connected throughsuitable gearing 24l to the rotor of the pump.

In accordance with the instant invention, the table 15 is adapted to berotated at slow speed by means of a suitable prime mover 25 which ispreferably an electric motor, the motor acting to drive the tablethrough a chain drive 26 and suitable reduction gearing, indicatedgenerally at 27, the gearing including a bevel gear 28 meshing with theperipheral bevel gear 16 forming a part of the table.

In accordance with the invention, the motor 25 is mounted in trunnions29 in such fashion that its stator or housing can rotate about the axisof its rotor in response to variations in its torque reaction. This maybe readily accomplished in numerous ways, as by providing the motorhousing with mounting rings 40a concentrically disposed with respect torotor shaft 41, thefmounting rings 40a 4being journaled in Vtrunnions 29by means of bearings 42. A spring 30 connected to the motor housingserves to balance the torque reaction, and an adjustable stop 30a ismounted on the motor housing, the stop contacting one of the trunnions29 and arranged to establish the desired initial balance of the motor.The motor housing also mounts an arm 31 which is connected by linkage3-2 to the carburetor or fuel pump 33 of the engine 23. With thisarrangement, and depending upon -whether the motor housing is rotated ina clockwise or counter clockwise direction, the linkage 32 will actuatethe carburetor t0 either accelerate or decelerate the engine and therebyvary the speed at which pump 21 is driven.

g In the operation of the device just described, the drill pipe 10 isrotated at a predetermined constant speed, which may -be in theneighborhood of 5 r.p.m. At the same time the fluid pump 21 will beoperating to supply fluid to drive the cutter bit motor 13. With thisarrangement, and with 4the motor 25 driven at a constant speed,variations in the torque reaction of the drill bit will be directlyreflected in the torque reaction of the motor 25.

For example, an increase in the torque reaction of the drill bitcoincident with a decrease in its speedas when a soft formation isencounteredwill cause an increase in the torque reaction of the motor 25as it seeks to maintain a constant speed of rotation. If the motor isturning counter clockwise, as indicated by the arrow A in FIG- URE 1,the increase in torque reaction of the motor will cause its housing torotate in a clockwise direction. This movement raises the arm SI1 andthrough it advances the setting of carburetor 33, thereby causing theengine 23 to accelerate and hence maintain the speed of the fluid pump2l which otherwise would be slowing down from the greater load thereon.This in turn results in an increase in the fluid flow to the cutter bitmotor 13 and hence serves to compensate for the increased resistance ofthe soft formation. If, on the other hand, the cutter bit encounters ahard formation, or if the bit -is off bottom or the weight of the bitlightened, its torque reaction will be decreased and, similarly, lthetorque reaction of the motor 25 will be decreased and the arm 31 willtend to move downwardly, thereby altering the setting of the carburetor33 and reducing the speed of the engine 23. This of course reduces thepower -to the pump 2l and the pressure to the cuttor bit motor 13,thereby causing the cutter bit to rotate at the desired constant speedand avoiding an excess speed. It will be understood, of course, thatboth the power input of the motor 25 and the tension of the spring 30will require balancing to obtain the proper proportioning and adjustmentof the parts. Simi- Alarly, the length of the governor linkage 32| mustbe yadjusteclfro-m time to time to assure proper speed of the drillmotor at various depths, as 4the pump requirement increases with depthof drill pipe. Any conventional form of mechanical governor linkage canbe used as well as hydraulic, magnetic, electrical or punched tapetypes.

In the embodiment illustrated in FIGURE 3 the fluid pump 21 is adaptedto be driven by a variable speed electric motor 34 connected by acircuit 35 to a speed control panel 36 having an arm 37 connected by alink 3S to the arm 3l of motor 25'. As before, the housing of motor 25is rotatably journaled in the trunnions 29 and, depending upon thetorque reaction of the motor, the arm 31 will raise -or lower the arm 37of the speed control device and thereby control the speed of the fluidpump.

In FIGURE 4, I have illustrated yet a `further modication of theinvention wherein the electric motor 34 which drives the fluid pump iscontrolled as to its speed by means of a servo-mechanism 39, whichservo-mechanism may comprise a moving iron solenoid 39a connected inseries with the power input to the motor 25 and responsive tofluctuations in the power input of the motor 25 as indicated by theammeter 49'. The power input of the motor will accurately reflect anychange in the torque reaction of the motor, that is, the quantity ofcurrent consumed will vary directly with the reactive torque of themotor, and by coupling the solenoid 39a to a rheostat 3915 supplyingcurrent to the pump motor 34, the current responsive Solenoid 39a willcontrol, the speed of the pump motor 34- which will be increased ordecreased in direct relation to the torque reaction.

Further modifications may be made in the invention without departingfrom the spirit of it. For example while in the embodiment of FIGURE 3,I have illustrated a servo-mechanism coupled to the ammeter 40, it willbe apparent that the variations of the power input could be noted by theoperator and the speed of the fluid pump adjusted accordingly. Asillustrated in FIGURE l, the ammeter 4t) may be conveniently mounted onthe motor 25, if so desired. A similar arrangement could be provided inthe embodiments of FIGURES l and 2 wherein the arm 3l connected to themotor housing could be used as a pointer movable over a scale whichwould indicate to the operator the proper speed for the fluid pump. Bothof these expedients, however, lose the automatic feature inherent in thepreferred embodiments of the invention.

Having however described by invention in certain eX- emplaryembodiments, what I desire to secure and protect by Letters Patent is:

l. In rotary well drilling apparatus, a drill string, a drill bit, afini-:l motor suspended within said drill string for rotating said drillbit, a pump for supplying fluid to said drill bit motor, means fordriving said pump, an electric motor for rotating said drill string at aconstant rate of speed, said electric motor having a rotor and a stator,said rotor being operatively connected to said drill string, meansmounting said stator for rotation about the axis of said rotor, meansresiliently biasing said stator in one direction, an arm on said stator,and linkage means connecting said arm and the means for driving saidpump, sai-d last named means having a movable speed control memberresponsive, through said linkage means, to movement of said arm.

2. The device claimed in claim l wherein the means for driving said pumpcomprises an internal combustion engine, and wherein said movable speedcontrol member comprises the carburetor thereof.

3. The device claimed in claim l wherein the means for driving said pumpcomprises a variable speed electric motor controlled by said movablespeed control member.

4. in combination in a rotary well drilling rig, a hollow drill string,a fluid motor secured to the lowermost end of said drill string, a drillbit connected to and driven by said fluid motor, a pump operativelyconnected to said hollow drill string for supplying iluid through saiddrill string to drive said drill bit motor, means including a drivemotor for slowly rotating said drill string, sensing means connected tosaid drive motor for sensing variations in the torque reaction of saiddrive motor, and means operatively connecting said sensing means andsaid pump and responsive -to variations in the torque reaction of saiddrive motor for varying the speed of said pump, said last named meansacting to increase the speed of said pump as Ithe `torque reaction ofsaid drive motor increases and cli-crease the speed of said pump as thetorque reaction of said drive motor decreases.

5. The combination claimed ink claim 4 wherein said drive motorcomprises an electric motor, wherein said sensing means comprises aservo-mechanism, such as a soienoid, operatively connected to the powerinput ofV said electric motor, said solenoid being responsive tovariations in the power input yto said motor and acting to increase anddecrease the speed of said pump in accordance therewith.

6. The combination claimed in claim 4 wherein said drive means comprisesan electric motor having a rotor and a stator, wherein said rotor isoperatively connected to said drill string, wherein said stator isrotatably mounted for movement relative to said rotor, wherein saidsensing means includes spring means biasing said stator in one directionand an arm on said stator, and linkage means operatively connecting saidarm to said pump, said pump including drive means having a movable speedcontrol member responsive through said linkage means to movement of saidarm.

References Cited in the file of this patent UNITED STATES PATENTS2,314,560 Scharpenberg Mar. 23, 1943

